Let's have a gander at the Optogate PB-05 E, available from Audio Technik. It’s a proximity triggered gate which is manufactured by Axel Joost Elektronik. It’s designed to block the signal coming from a microphone if nobody is near it, which gives it a very handy application in live sound. Let's go through how it performed when used for recording a few episodes of Soundcheck, and comment on applications where it is useful and applications where it borders on redundant.
Before we check out it’s application, let’s take a closer look at how it works. The front end plugs into the microphone, and the back end plugs into and XLR cable leading to your console or interface. It requires 48V phantom power, and this particular model is designed to work only with dynamics, as it presumably lacks the capability of passing on power to an active microphone such as a condenser. There are other models which can be used with condensers, the PB-05 D and the PB-05 M. The PB-05 D attenuates -42dB when the gate is closed, and both other models attenuate at -16dB. Apart from these differences, all three models perform the same.
On the front of the gate is an infrared proximity sensor and a red light which indicates when the gate is open (or effectively, when the microphone is on). On the side is a trim pot used to change the threshold distance. It’s a small screw, which means you’ll need to keep a small phillips head screwdriver handy. The distance can be changed between 15cm and 120cm, and should be calibrated to each performer. This is where things can get a little bit tricky.
The first time we tried to use it, I forgot to bring a screwdriver. That leaves my first critique of the design. I get that it’s not that difficult to make sure you have a screwdriver on hand, but how hard is it to create a trim pot which can be calibrated with human fingers?
During the filming of our next episode of Soundcheck, calibrating the gate was easy enough because I remembered to bring a screwdriver. But then came the main issue many sound engineers will face when using the optogate. We were trialling the optogate with Jamie, the guitarist and backup singer for Adrian Dzvuke. I asked him how far back from the mic he will stand, and we set the distance threshold accordingly. It was set a little bit further back than he said he would be singing, because I’d rather hear some extra bleed than experience Jamie singing into a closed gate.
Luckily, during the sound check of Soundcheck, I noticed that Jamie’s gate was closed the whole time he was singing. He was standing three or four inches further back than he said he was going to stand, and I don’t blame him. How can you expect a guitarist/back up singer to be hyper aware of how far away they are from a microphone, during a live setting, when they’ve never had to think about that before? You essentially have to set the distance a bit further back than the ideal distance, because it’s better to have more bleed than a singer who’s not being heard. Then you’re faced with another question entirely; is it better to experience bleed dropping in and out, or to have a constant bleed that peoples ears get used to? This same question applies to foldback, imagine how distracting it must be for drum bleed to be coming in and out of your IEMs while you’re trying to perform.
Don’t get me wrong, I’m not saying that the device is useless, but that if a musician is untrained with optogates, then the presence of the device can introduce its own problems to deal with. But if you had a well trained, and predictable singer, it would work great. This is why I’d highly recommend this device for musicians to carry with them wherever they play. As a singer, if you set the threshold to the right distance for you, after some practice you’d be able to set it to very accurately cater to your performing style. You could take it wherever you go, and just ask the sound engineer to send phantom power. Just like magic, you’d have a cleaner sound and cleaner foldback. That’s a very useful device!
Like most audio gear, the optogate can be very useful if applied with care in the right circumstances; and yet in the wrong situations it can create more problems than it solves. For example in a recording environment, it’s function is redundant, because you can just delete all of the moments where the signal is 100% bleed and then you’re left with the output of an optogate with no risk of a mistake that’s been committed. It’s right place is in a live environment, where bleed is unwanted, but can’t be treated reliably with a normal gate; which often opens for loud bleed and closes for direct signal which is too soft. The main consideration in a live environment is that many musicians will need to be trained to sing with optogates to avoid the device introducing other problems. I’d still recommend they be added to the arsenal of most sound engineers, but highly recommend that musicians who are serious about their sound should buy a few of these to use at all of their gigs.